1. Field
The present disclosure relates to a composite anode active material, a method of preparing the composite anode active material, an anode including the composite anode active material, and a lithium secondary battery including the anode.
2. Description of the Related Art
Due to high energy density and convenience in design, lithium secondary batteries have served as a main source of electrical power of mobile electronic devices, and the application of the lithium secondary battery using as a power source of an electrical vehicle or an electrical power storage device of renewable energy has been broaden out. In order to match this demand of the market, studies on materials of a lithium secondary battery having high energy density and long lifespan characteristics have been continuously carried out. Among anode materials, for example, studies on various materials such as silicon, tin, or germanium, as well as carbon have been conducted.
Among the anode materials, a silicon material has high energy density compared to that of a graphite material, which is commonly used as an anode active material. However, when a silicon material is used as an anode active material, an unstable solid electrolyte interface (SEI) layer may be formed by a side reaction between a silicon surface and an electrolyte, which deteriorates electrochemical characteristics of the anode active material. Also, due to internal stress caused by rapid volume expansion that occurs during a charging/discharging process, the silicon material may be pulverized. Therefore, a composite anode active material that may prevent formation of an SEI layer by suppressing a side reaction between a silicon surface and an electrolyte and may suppress rapid volume expansion that occurs during a charging/discharging process is needed.